Herman a



gan. 29 1924.

H. A. AFFEI.

REPEATER FOR MULMPLEX SYSTEMS Filed sept.' 26

INI/EN TOR. HAAHM ATTORNEY Paenlietl dan. 29, i924. ll

lylilililifnlll ll?) il f llTll.

HERMAN A. AFFEL, OFBROOKLYN, NEW YORK, ASSIGNOR TO AMER-TLCAN TELEPHONE ND TELEGRAPH COMPANY, A CORPORATION DF NEW YORK.

REPEATER FOR MULTIPLEX SYSTEMS. Application tiled September 26, 1919. Serial No` 326.515.

To all' iii/tom 'zii mg/ @0f/merit.: 'lli through transmitting clinnnils; TLX. 'I`L;, lo it known than, l. llnmmx FFEI.. und 'l`li. rosliol'iivvl'if. The: linnn lil. li., :ind resii'ling nt` liiooldi'n, in the ronnty ol Kings lig nro siniilnrly nsnioiizited with tli rromand fltntie ol Non' `toi-li, huw invented cGrnion rinvii-ing virrnit through roi'liii'in.;r 5 tnin lniiiroriinonts in -lxeyinniors t'or Mnlti- Channels ll'lil'. lili2 :ind Klim rifsiiritivili'.

plm; iii'btinin, ot which tho l'iillowixngr is n .ln order lo translate they lon' froqnonry spncifiviiiinn, signals into niodnlnted i'nrricr 'i'inriints of This invention rilnteo lo ninltiiilix trnnsdillorcnl frodininiinnl niodnlntors lill. M2 und InisSion und nioro particnlnrly to ropnlvr lll,i :irll providod in thi` Sover-nl trnnsniitiinj;l 10 circuito l'or nso in ninltiplox systems. (loo ilinnnvl. Thorlniodnlntors nini4 liol ot' nn)v U5 of tho rzitnros olr the invention rosidts in \\'0ll-l no\\'n ti'iin. lint nriI oreilly-nhl)v rnrnnni the provision ol' :i repeater nrrzingonwnt tnlii inodnlntoi so nrrninfid thnt dill'irvnt for n multiplex :siro-toni. in whirh oppositiily r-:irriiir t'rviiniinifilis Qniiiilii-d tliiiri-lo will lio llirvctod transinisnlons tok@ plano nly dillfrvnt niodidiitid in nvrordnni-o wil li low l'riqinin'-v 5 frtiqininrioii. the rr-pontnr riri'nit liningl so nr- Signals. ln ordiir to nniintnin :i lriiinonrv 70 ranged that :ill ol' tho trnnnniissions in ont .wiizirntion liiilnoin the #Moral trnnsniisdiroftion will lio ninnililiiid liy ono onowny sions. tl'iii-iirrior 'lriiqnrnwiw sinililiiid lo tho ,repent/ilo' and :ill of tho translnissiioml tnkinir inodnhitor should liv dill'irint :ind l'or linz*- plzico in the opposite direction will lio nnipliposo# fil' illnsirnlion tliiA rnrriiir l'riqinin'ies :o fied o5vv another one-wily ripvnti'r. niiiilird to tho niodnlzitors M1. M2 :ind M3 75 Anolihor feature of the ini'iintion whites :irlx indirzitid niiiin tho ill-1min@ :is lining to thoprovision ol :i repeater circuit, in n, Mino ril-lon, tation iii-wlw :ind Illini! cyclos. multiplex systeni ol the rhin-artnr nliovo doriisyioiliroly. lt will Iiil nndvrntood, ot' scribed, said repvnter oirrnit' livingso :ir- Join-sv. thiny thiisn t'roqnonwii-s :irinniroly ilrnngd that oppositely directed trnnsniiw lnntrntivo :ind tl'ini in println-i :in r snitnlile S0 sions will he separntod by moans ot linlnnrA 'l'rnqininciiis nin) lio hoorn whivh vxisting ing;l arrangements nnditho fpnrntion dno to rondit ions` will wnrrnnt. l `iltcring nlrnngobollino@ will he Al'intiher inirefisid li'iv :1 t'ronn^nt 4 Tlf.. 'lli :ind Tlf.l nrti also provided qnency sfiiairnt-ion betwoin the oiiositely VFor this Irnnsniiiiint hanna-ls. in order to :1.0 diroct'od'channels. ninintnin n lriiqnoiii-.v soiinrntion between 85 These faitnres, together with othir for.A lin-ni. Thi-so l'illonv4 niny lio oithor tnnod rirtures ofthe inontion more fnlly hnriinnl'tor units il tiny n'olhknon'n type, or they nnly zijipenring-,ore realized by the nrrnnguinonts litl linnd iltorn o1" tho typo disiloSvd in lli(` not forth in the following description :ind ll. S. lhitonts, Non. 1,927,113 :ind 1.227.114. disolosld in the ncooniiinnvin"r drzin'ingf. tho ins-nod to George A. (lnniplioll nndcr dilleY ligg'nroof which illnstrntos in sinnililiid torni oi .-iliiy 29. lill?. 1Whore linnd filtern nro one mnliodimont ol" thil iin'onl'ion. i niniilojifid thoy .should lilx so dvsignvd as to In the drawing'n lllli dosignntos n nniin trnnsniit :i linnd oi froqiwi'irivs in thii neighlinv section ilxtendingg from n roiionter stnliorhood of tho inrriir lrcqni-*niy':iSSigrnod to i0 tion to a terminal ninltiiilvx Currier station. the rlinnnvl. lho linnd lining ot' sntliciont :i5 at 'Whit-h snitiililo npi'iznntns is nrrnnnnd to width lo :nwiininnidntc the treqneni'y varia s :nporpow :i Iilnrnlitli' ol' signnls on thil lino. tion dnll to niodnlntii'in. llt tho tirniinnl nnrltiiilnx station :1 ronniion ln ordm' to amplify the Svi'ornl Cnrriir transmitting xiii-nii TlA is n. ii-.^int -.l `willi lrvqinni-irs whicfli :iro inlprissvd npon thv 45 thv moin lino through :i lizilnnriid trinwijonnnon trnnsniinsion circuit TL. :in nniiliffloo forinor nri'nngonnint itl. n'hilc :i voniniiin rilivr Tft is; providvdin snid fironit Tl). This Cviving ('iiinit' i lii'idgjid nvrosslnj niid :iniiililiiir nin)v lio of any woll-known type. pointy oi thu lintl windings ol" llir tiniislint if; lorelirnlily nn :unplitii-r of tho wolllorniir lll. ln omitir to runder thv riri'nds known i'ni'fnnni tnlie typo. A iltnr TF is 5t? Tli und lllJ -oninnnrno nitli rvs-)wvl lo moll nlso provided in tho circuit, TL, this filter 105 othir. tho ninin lin@ llli is linlnnil-d liy nn living prefornlilv n linnd filtor. oi' thi.l typo artifit'inl lim` or network MX, l.. :ind disrliisnd in .tlio :iliovo nlentli'onod, pntvnts to l@ donigfnnlo n plnrnlity o.F lon' i'roiiinniir ('tnnpbi'll. Tho filter Should lm SO designed 1 signaling vin-nits, those circuits lining nsh'o- :is to transmit n hand of frequencies sulliifintifd with 1li@ .-onnnon transmitting circuit cicntly wide to accommodate all of the 110'.

-' transmit a band of frequencies sufficiently quencies use Wide to accommodate all of thefrequencies` to be transmitted tothe several receiving channels. Where the systemis arranged as hereinafter rescribed, so that the frefor transmitting will all lie inone range, While those used forreceiving will lie in another range, the filter RE will,

I of course, be designed to transmit a different band of frequencies from the lter'TF.

In this manner Athe separation between 0p-V positely directed transmissions provided by alance will be supplemented by frequency separation. The amplifier RA will in general be similar to the amplifier TA and serves a similar purpose nitlijrespect to the received carrierV currents.

' Filters RF1, RF2 and RF., are included in the receiving channelsRL1. RL2 and RLB,

respectively. These filters may be either tuned circuits or band filters of the Campbell type, and in the latter case should be so designated as to transmit a band of freuencies in the neighborhood 4of the carrier requency assigned to each receiving channel. In the case illustrated the frequencies used for receiving are in an entirely differi ent range from the several frequencies used for transmitting and consequently the filters are designed to transmit frequencies vin the neighborhood of 15,000 cycles` 18,000 cycles and 21.000 cycles, respectively. It will be understood, however, that other frequencies than those indicatedv may be utilized.

Detectors DI, D.Z and Dl, are also included in the receiving channels. These detectors may be of any Well-known type. but are preferably vacuum tube detectors operating upon the homodyne principle of receiving. Consequentl the detectors are supplied with unmo ulated currents of the carrier frequency assigned to the channel, these frequencies being, as above stated, 15,000, 18,000

, and 2.1.000 cycles. The unmodulated carrier currents supplied to the detectors interact withj the received modulated carrier currents. so' that the low frequency signals in accordance with which the received carrier currents were modulated. Will appear in the output circuits of the detectors.

At the repeater station the mainline'ML .is associated with aneastbound repeater channel, ELand .af westbound repeater channel WL, through a balanced transformer arrangement. 20, the channel 'WL beingconto theimidpoints of the line windings f )ffi'said transformer. In order to render'the o `repeater channels substantially.` con- .rier currents received by the channels RL,.

of a network N. A similar line ML leads from the repeater station to another ter minal carrier arrangement (not shown), similar to that already described. Said main line ML is likewise associated with the east and west bound repeater channels, through 4a balanced transformer arrangement 20', -tlie eastbound channel EL bein connected to the midpoints of the line win ings of the transformer. The channels EL and WL are rendered. substantially conjugate as regards the line ML', by means of a network N for balancing said line.

Repeaters AE and AW are included in the 'lines EL andWL, respectively. These repeaters may be vof any well-known type. but are preferably amplifiers of the wellknown vacuum tube type, so designed as to amplify a plurality of carrv 1ing frequencies;

In order to supplement t e separation between east and west bound transmissions, which is due to balance, means for permitting of frequency separation between-the oppositely directed, transmissions are provided. Said means comprise band filters EF and EF on either side of the amplifier AE and band filters VF and WF' on either side of the amplifier AW. The filters'EF and EF are premirbly band filters of the Campbell type, already described, and are so designedas to transmit a band of frequencies sufficiently wide to accommodate -tlie several modulated carrier fre uencies R112 andRL3 and therefore for purposes of illustration these filters are indicated as transmitting a band lyingbetween thirteen and twenty-threethousand cycles. The exact frequencies assigned to the several chan-alla` nels and the frequencies transmitted by tin",v

-various filters may. of course, be varied as conditions require. i

The operation islas follows: Low fref l quency signals incoming from the lines L1,

'L2 and L.,v are transmitted into the transmit ting channels TLL, TL 'and TL.1 and areI t yimpressed upon the modulators M1, M, and M respectively, tn modulatefthe carrier fre-l uencies assigned tothe gsevgizljalichannels. )2 6 he modulated carrier f 'uenciesaet en passed through thel'ltexfs. i ,TFjnnH F and after passing into the common `mitting circuit TL'are amplifiedifbythe!y Plifler Terrasse@- thtoug the filter dll transmitted through the transformer 10 to the main line ML. As the transmitted modulated frequencies lie Without the band passed by the filter RF, any transmitted energy impressed ,upon t-he common receiving` circuit lila, due to imbalance, will be suppressed by said filter RF. After transmission over the main line ML the modulated carrier frequencies are transmitted through the transformer 20 into the east! hound channel EL. These frequencies will, of course. he prevented from being substantially direrted into the westbound channel "Villa by reason of the fact that the filter Wl" passes a band of frequencies lying without the range of frequencies employed for transniission in an eastbound direction. The frequencies transmitted to the eastbound repeater channel EL pass through the filter l) l" and are amplified by the amplifier Arlt. The amplified frequencies arev then passed through the filter EF and are then impressed upon the midpoints of th `line, windings of the transformer 20', so

that half of the energy flows over the maan line Ml] to the distant station and the other half flows to the balancing network N1. Such energy as may be impressed upon the. westbound cnannel WL, due to imbalance, is substantially suppressed by the filter WF.

The modulated carrier currents transmittod from the distant station and incoming from the line lli/lli. are transmitted through the transformer 20 to the westbound channel Wl) and passed through the filter 7F to the amplifier All". After being amplified hy the, amplifier AW, the amplified frequenries are passed through the filter WF and are then impressed upon the midpoints of the tine windings of the transformer 20. so that part of' the energy flows to the artificial ,line hi and part to the main line ML. Any energy impressed upon the eastbound channel llfi. due to imbalance will, of course, he suppressed by the filter EF. The several frequencies transniitted over the main line lelli are prevented from reacting upon the transmitting circuit TL. by means of the filler TF and flow through the filter R f` into the receiving channel lili. The several fr uencies are then amplified by the amplifier -A and are selected by means of the lters RF1, lil@ and RF 1,. respectively. The modulated carrier currents received in these channels are now detected by means of the detectors 1),. lh, and l), in a well-known manner and the resultant ylow frequency signaling Currents1 are transmitted over the channels to the low frequency signaling lines' Ll-,QLW and la. respectively.

While the system, described, provides for only three signaling circuits, it will be understood that additional signaling o ircuits may be provided, if desired.

consequently the frequencies It Will further be obvious that the general principles herein diselosedniay be embodied in many other organizations Widely dfferent from those illustrated, Without departing from the spirit of the invention as defined in the following claims:

What is claimed is:

l. ln a signaling system, a transmission line, means for transmitting signals in one direction over said line by nie-ans of currents of one frequency, and means for transmitting signals of' the saine kind in the opposite direction over said line by means ofvcurrents of another frequency. a one-way repeater in said line for amplifying currents of the frequency transmitted in said first mentioned direction. and a sccond one-way repeater for amplifying eurrents of the frequency transmitted in the opposite direction. i

2. In a signaling system, a transmission line, means for transmitting sinmltaneously a plurality of signals over said line in one direction by means of' currents of different frequencies, means for simultaneously transmitting in the opposite dir-ection a plurality of signals by means of currents of other frequencies, one-way repeating apparatusin said line for amplifying only currents transmitted in one direction and other one-way repeating apparatus in said line. for amplifying only currents transmitted in the opposite direction.

ln a signaling system, a transmission line, means for simultaneously transmitting over said line in one direction a plurality' of signals by means of currents of a plurality of frequencies lying within one f'requeney range. means for simultaneously transmitting over said line in the opposite direction a plurality of signals by means of a plurality of currents of different frequencies lying,r within another frequency range, repeating apparatus ir. amplifying currents within the one frequency range2 another repeating apparatus for transmitting currents lying within the other frequency range, and means for balaneingksaid transmission line with respect to saidl repeating apparatus.

In a signalingl system, a transmission line, means for simultaneously transmittingV over said line a plurality of signals by means of currents of a plurality of frequen` cies lying within one frequency range. means for simultaneouslytransmitting in the opposite direction over said line a plurality of signals hy means of currents of different frequeneies lying with another and entirely different fre uenev ange a common repeater for amp ifying` all of the frequencies within the first mentionedrrange, another common repeater for amplifying all of the frequencies within the second range, and means for balancing' said transsaid line for ffl 4 i il".

il mission line with respect to said repeating means for Atransmitting another and entirely different range of frequencies over said line in one direction,

' cuit arrangement for vtransmission in one` direction, `for.'transniission in the opposite direction,

transmitting iii one direction,

in the opposite direction; a two-way repeater in saidiline comprising acirtuit vfor transmission in one direction, and another circuitpfor transmission in the opposite direction; means for balancing said ransmission line with respect to said rep, ater circuits; an amplifier 4in each circuit, and selective means in one of said circuits on each side of the amplifier therein, for passing -the range of frequencies used in transmitting and selective means lin the side of the amplifier the range of frequenin the, opposite diother circuit on each therein, for selecting cies used in transmitting rection. Y

l 6. In a ,signaling system a transmission line, means for transmitting one range of frequencies' o'versaid line in one direction, means for transmitting another and entirely different range of frequencies over said line in the oppositef'directiong/fa Vtwo-way repeater in said line, said repeater comprising a circuit for transmission Iin one direction,

i and another circuit for transmission in the opposite direction; means f or balancing4 said ltransmission line wth-crespect to said repeater circuits; an amplifier in each circuit; Va hand filter on each side of the amplifier in one circuit for passing the range of fre quencies transmitted in one direction and suppressing the range of frequencies transmitted in the opposite direction," and a band filter on each-side of the amplifier in the other 'circuit for freeiy transmitting the range of frequencies transmitted in the opposite direction, and for suppressing the fre uencies transmitted in the first direction. -Y 7. In a signaling system, a transmission line over which a plurality vof signals may fbe simultaneously transmitted in opposite directions, the frequencies used for transmitone direction t' a pini' nty of signals in di ering from the frequencies used for transmitting@ corresponding plurality.

of in ltlieopposite direction, repeating signals apparatus in said line comprising a cir- 1 and another circuit arrangement amplifying apparatus associated with. each circuit arrangement, and selective means .associated lwith one of said circuit arrangeinents `oneaeh sideof theamphiying ap the frequencies' used in and selective means inA the other circuit arrangement on each` siderpftlie amplifying apparatus for Paratus. for passing selecting the range of frequencies used in transmitting in the opposite direction.

8. In a signaling system, transmission line sections, one-Way transmission paths nterconnecting said line sections', and frequency selective means whereby frequencies transmitted in oney direction over said line sections will pass over one of said paths, and whereby frequencies transmitted in the opposite direction Will pass over the other of said aths.

9. n a signaling system, transmission line sections over which a plurality of signals may be simultaneously transmitted in both directions, a circuit arrangement interconnecting said line sections for transmission in one direction, another circuit ar- 1angement interconnecting said line sections for transmission in the opposite direction, frequency selective means for selecting into one of said circuit arrangements a plurality of signals transmitted over said line sections in one direction, and preventing transmission over said circuit arrangement of signals transmitted in the opposite direction, and frequency selective means associated with the other circuit arrangement for selecting into the said circuit arrangement a plurality of signals transmitted in the opposite direction,

and requency selective means in the other path whereby frequencies transmitted over said line sections in the opposite direction will pass over said path to the exclusion of said first mentioned path.

ll. In a signaling system, transmission line sections, one-way paths interconnecting said line sections, one-way repeaters in each path, frequency selective devices in one of said paths on each side of said repeater whereby frequencies transmitted over said line sections in one direction will pass over isaid path to the exclusion of the other path,

and 4frequency selective means in the other ath on each side of the repeater therein whereby frequencies transmitted over sai line'sections in the opposite direct-ion will pass over said path to the -excliisioii of said first mentioned path. i,

In testiinoi'iy whereof, 1 have signed my name to thisspeciicatieiithis 25th day of September, 1919.

yiinzaMAN A. Arran-f i transmission iio 

